Preheat the oven to 350°F (175°C). Grease and flour two 9-inch round cake pans; line the bottoms with parchment for easier removal.

In a medium bowl, whisk together flour, baking powder, baking soda, and salt. Set aside.

In a large bowl, cream the butter and granulated sugar with an electric mixer on medium until light and fluffy, about 3–4 minutes.

Add the eggs one at a time, beating well after each addition. Mix in 1 teaspoon of vanilla.

In a separate bowl, stir the whole milk and sour cream until smooth.

Add the dry ingredients to the butter mixture in three additions, alternating with the milk/sour cream mixture: dry, wet, dry, wet, dry. Beat on low until just combined — don’t overmix.

Fold in the melted white chocolate gently with a spatula until streaks disappear.

Divide batter evenly between the prepared pans and smooth the tops.

Bake 25–30 minutes, until a toothpick inserted into the center comes out clean or with a few moist crumbs.

Cool in pans for 10 minutes, then invert onto wire racks to cool completely.

While cakes cool, make the raspberry filling: mash 1.5 cups fresh raspberries and stir in raspberry jam until combined. Taste and adjust sweetness.

Make the whipped cream: beat 2 cups heavy cream, 2 tablespoons powdered sugar, and 1 teaspoon vanilla on high speed until stiff peaks form.

To assemble: place one cake layer on a serving platter, spread the raspberry mixture evenly over it, then top with a generous layer of whipped cream.

Place the second layer on top and press gently. Frost the top and sides with remaining whipped cream.

Garnish with fresh raspberries arranged decoratively. Chill for at least 1 hour before slicing.